In the relevant field of patient transport ventilators, a wide range of devices to aid breathing are known. The invention relates to an automatically operated transport ventilator typically used in trauma situations by hospital and ambulance crews, firefighters, military medics, and the like during life threatening emergencies.
Simple transport ventilators amount to a hand held mask fitted over the patient's nose and mouth, with a manual valve to control breathable gas flow from a pressurized source of gas. Typically pure oxygen is provided in portable metal cylinders or from built-in gas conduits in a hospital setting for example. Air is optionally mixed with the oxygen through an in-line venturi mixer.
The prior art includes several advanced means to control and monitor the flow of breathable gas under pressure between the gas source and the patient mask. Since the patient may be in different states, i.e.: unconscious and not breathing; breathing sporadically; or breathing independently, and may shift between such states unpredictably, manual control means which require constant operator attention and control are not preferred.
A fully automatic transport ventilator is described in U.S. Pat. No. 5,520,170 by the present inventors, for example. The obvious advantages of full automation include lowering the level of training and competence of the operator, and enabling the operator to concentrate fully on other emergency duties while resuscitation proceeds untended.
A disadvantage of such automatic devices however is the danger inherent in a lack of supervision. For example, several dangerous conditions may arise suddenly or the operator may desire notification of changes in the patient's condition.
If the supply of breathable gas is depleted, the patient may suffocate due to the air tight nature of the mask and the automatic device may cease to operate. If the mask leaks or becomes dislodged, the patient does not receive the intended gas flow and pressure for optimum resuscitation. If the pressure of gas supplied to the patient is too high, the patient's lungs may be damaged, whereas if the gas supply pressure is too low, the resuscitation does not proceed as intended.
It is desirable therefore to produce an automatic transport ventilator device that includes means to control and monitor the device, as well as to notify the operator of various important changes in the status of the patient and device. In particular it is desirable to provide such functionality with a minimum of additional operator training and mechanical complexity.